Orthotics (Greek: Ορθός, ortho, “to straighten” or “align”) is a specialty within the medical field concerned with the design, manufacture and application of orthoses. An orthosis (plural: orthoses) is “an externally applied device used to modify the structural and functional characteristics of the neuromuscular and skeletal system”. An orthosis may be used to:
- Control, guide, limit and/or immobilize an extremity, joint or body segment for a particular reason
- To restrict movement in a given direction
- To assist movement generally
- To reduce weight bearing forces for a particular purpose
- To aid rehabilitation from fractures after the removal of a cast
- To otherwise correct the shape and/or function of the body, to provide easier movement capability or reduce pain
Orthotics combines knowledge of anatomy and physiology, pathophysiology, biomechanics and engineering. Patients benefiting from an orthosis may have a condition such as spina bifida or cerebral palsy, or have experienced a spinal cord injury or stroke. Equally, orthoses are sometimes used prophylactically or to optimise performance in sport.
Manufacture and Materials
Orthoses were traditionally made by following a tracing of the extremity with measurements to assist in creating a well fitted device. Later the advent of plastics as a material of choice for construction necessitated the idea of creating a plaster of Paris mold of the body part in question. This method extensively is still used throughout the industry. Currently CAD/CAM, CNC machines and even 3D printing are involved in orthotic manufacture.
Orthoses are made from various types of materials including thermoplastics, carbon fibre, metals, elastic, fabric or a combination of similar materials. Some designs may be purchased at a local retailer; others are more specific and require a prescription from a physician, who will fit the orthosis according to the patient’s requirements. Over-the-counter braces are basic and available in multiple sizes. They are generally slid on or strapped on with Velcro, and are held tightly in place. One of the purposes of these braces is injury protection.
Under the International Standard terminology, orthoses are classified by an acronym describing the anatomical joints which they contain. For example, an ankle foot orthosis (‘AFO’) is applied to the foot and ankle, a thoracolumbosacral orthosis (‘TLSO’) affects the thoracic, lumbar and sacral regions of the spine. It is also useful to describe the function of the orthosis. Use of the International Standard is promoted to reduce the widespread variation in description of orthoses, which is often a barrier to interpretation of research studies.